Proving 1 isn't in my group

I need to show my group is closed under *, and I'm happy with my proof that all of the possible outcomes are rational numbers. So now I need to show that 1 is not a possible outcome. Is my proof of this acceptable?

Assume

Therefore,

Last edited by beebe; Dec 13th 2011 at 05:17 PM.
Reason: Prettying up the formatting

Re: Proving 1 isn't in my group

Originally Posted by beebe

I need to show my group is closed under *, and I'm happy with my proof that all of the possible outcomes are rational numbers. So now I need to show that 1 is not a possible outcome. Is my proof of this acceptable?

Assume

Therefore,

it is correct but I think you just need to modified it like this want to prove that for all
your proof is by contradiction so we will say
suppose in the contrary that there exist such that